What condition is characterized by parallel rays of light focusing at a point just in front of the retina?

The condition characterized by parallel rays of light focusing at a point just in front of the retina is myopia, also known as nearsightedness. In myopia, the shape of the eye causes light rays to converge too soon, which means that objects at a distance appear blurry while close objects can be seen clearly. This occurs because the eyeball is either too long or the cornea has too much curvature, preventing the light from focusing directly on the retina.

Understanding myopia helps differentiate it from other conditions. For example, hyperopia, or farsightedness, occurs when light rays focus behind the retina due to the eyeball being too short or the cornea having insufficient curvature. Astigmatism results from an irregular shape of the cornea or lens that prevents light from focusing evenly, leading to distorted vision at various distances. Presbyopia is an age-related condition where the lens becomes less flexible, making it difficult to focus on close objects, but it does not relate to the focus of parallel rays in the manner described.

Therefore, myopia is the correct choice because it effectively explains the specific condition where light focuses in front of the retina.